Adapted from the Applicant?s Abstract) This Core will provide essential technical facilities for microscopic and morphometric studies of muscle and other tissues. Throughout the 25 years of this PPG, the investigators have always taken the stance that structure should be correlated with function. During the first two cycles of the Program Project, extensive use was made of the technique of rapid freezing of lung combined with preparation of tissue for transmission electron microscopy under the direction of Dr. Mazzone. When Dr. Mazzone left, 15 years ago, Dr. Odile Mathieu-Costello replaced him as a faculty member. Her primary interest is in structure-function relationships, especially in skeletal muscle as evidenced by her Project 3 in the 4th cycle , and Project 2 in the previous cycle and in this proposal. She has also closely collaborated with Dr. John West over the past 9 years on the electron microscopy and morphometry of stress failure of pulmonary capillaries. She was trained as a morphologist by one of the leading authorities in both lung and muscle morphology and morphometry, Professor Ewald Weibel from Switzerland. She brings unique expertise to this highly specialized area, and she is the ideal person to continue to head the scientific aspects of this Core. The investigators see the Morphology and Morphometry Core as an essential feature of the Program Project. The Core will also fully support the salary of Li Wu, the histology technician, as in the previous cycle. Mr. Wu has experience in the preparation of sections of muscle and other tissues for light and electron microscopy, and histochemistry. He will work closely with Dr. Mathieu-Costello in the preparation of tissues for both light and electron microscopy, Mr. Wu understands the needs of our group well, and is well trained in the execution of tissue preparation and morphometry. Morphometric analysis requires a large number of sections and fields to be examined, and tissue sectioning, especially for electron microscopy, is extremely time consuming. Based on the output of the Core in the past cycles and the studies proposed in this application, a full time technician is clearly needed to meet the needs of the different projects.